This invention relates to a filtering apparatus for filtering cutting oil containing metal pieces which are referred to as "metal chips" produced during metal cutting operations in a metal working machine.
There have been proposed and practically employed a variety of apparatus for filtering cutting oil containing metal chips; and one type of the prior art filtering apparatus is disclosed in U.S. Pat. Nos. 1,630,274, 2,014,144 and 3,979,289, for example. As shown in these U.S. patents, a filtering drum having a filtering screen extending about the periphery thereof is rotatably mounted within the cutting oil reservoir and during operation, cutting oil containing metal chips is introduced into the filtering drum which separates the oil and chips from each other and the separated metal chips are allowed to settle within the filtering drum to be carried out of the drum whereas the filtered cutting oil is allowed to flow from the drum into the reservoir.
However, the above-mentioned filtering apparatus has the following drawbacks:
In the prior art filtering apparatus, since cutting oil containing metal chips is introduced into the filtering drum, the total weight of the chips and oil is directly applied to the filtering drum. As a result, a specific mechanism for journalling the filtering drum within the oil reservoir has to be provided. In addition, the filtering screen extending about the periphery of the filtering drum should be designed to withstand potential damage from the metal chips contained in the cutting oil.
Furthermore, means for depositing the metal chips separated from the cutting oil within the filtering drum and means for carrying the deposited of metal chips out of the filtering drum should be specially designed.